Exposure to chemicals is capable of initiating abnormal clinical presentations. In most cases the degree of exposure determines whether toxicity-enhancing processes (usually at play after toxic agent administration) overwhelm toxicity-preventing ones. The study is embarked upon to compare the degree of toxicity that is associated with two doses (0.5 and 1.0 mL/kg body weight) of engine oil exposure, after 30 days of daily administration. Thirty adult female rats (200-240 g) were divided equally into five experimental groups. The first and second groups were treated with 0.5 and 1.0 mL/kg through the dermal route respectively while third and fourth groups were treated with 0.5 and 1.0 mL/kg through the oral route respectively. The fifth group served as the control. Serum obtained from blood collected by retro-orbital bleeding was stored at - 20ºC until required for analysis. Serum levels or activities of hepatorenal markers (alanine/aspartate aminotransferase, alkaline-phosphatase, γ- glutamyl transferase, total-protein, albumin, urea, creatinine) were investigated using standard techniques. The mean values of all estimated parameters were analyzed using analysis of variance, p≤0.05 was considered significant. Results revealed that both doses caused significant differences in most of the markers (urea, creatinine, albumin, globulin, hepatic enzymes) but the degree of alteration was more pronounced in the higher dose of 1.0 mL/kg than lower dose of 0.5 mL/kg. Data obtained through the study suggest that even low dose exposure can result in hepatorenal toxicity. Therefore exposure to engine oil from environmental contamination, occupational contact or deliberately for cosmetics/ therapeutic reasons should be avoided.